Solvent refining of motor fuels



Patented Nov. 19, 1940 UNITED STATES SOLVENT REFINING F MOTOR FUELSWilbur B. Pings, Wilmington, Del., assignor to E. I. du Pont de Nemoul's& Company, Wilmington, Del., a corporation of Delaware No Drawing.Application June 30, 1939; Serial No. 282,072

17 Claims.

This invention relates to the solvent refining of motor fuels and moreparticularly to. the production of motor fuels of relatively high knockrating from motor fuels having relatively low knock rating.

'Motor fuels derived from crude petroleum oils by direct distillation,known as straight-run gasolines, are in general too low in octane valueto be used per se in the high compression engines of today. These fuels,as well as the cracked gasolines and polymer gasolines, are ordinarilycomposed of mixtures of paraffinic, naphthenic, aromatic and unsaturatedaliphatic constituents which vary widely in their resistance to knockingin high compression internal combustion engines. It is generallydesirable to improve the knock rating of such motor fuels or to obtaintherefrom motor fuels of higher knock rating. I have found that, bysolvent refining such mgtor fuels employing a certain type of solvent, Ican separate, from such motor fuel mixtures, the constituents ofrelatively high knock rating.

It is Well known that the more viscous petroleum oils can be refined bymeans of solvents to separate the relatively non-paraffinic constituentsfrom the relatively paraflinic constituents. Many solvents have beenproposed therefor and have been employed successfully. Many of suchsolvents cannot be employed with the non-viscous oils of motor fuelboiling range, as they will not form the essential two phases atobtainable temperatures, or cannot be separated from the severalfractions of the motor fuel.

It is an object of my invention to provide a method of treating anon-viscous, normally liquid hydrocarbon oil of motor fuel boiling rangecontaining relatively parafllnic and relatively non-paraflinichydrocarbons to separate the relatively non-paraffinic hydrocarbons fromthe relatively paraflinic hydrocarbons. Another object is to extract therelatively non-parafiinic hydrocarbons from a non-viscous,-normallyliquid bydrocarbon oil of motor fuel boiling range by means of aselective solvent. A further object is of improved knock rating from anon-viscous, normally liquid petroleum oil of motor fuel boiling range,which comprises a mixture of hydrocarbons of different knock ratings byextracting the hydrocarbons of relatively high knock rating therefrom bymeans of a selective solvent. A still further object is to provide amethod of producing a motor fuel of improved knock rating from astraight-run gasoline. Other objects are to improve the art. -Stillother objects will appear hereinafter.

These objects may be accomplished in accordance with my invention, whichcomprises subjecting a non-viscous normally liquid hydrocarbon oil ofmotor fuel boiling'range containing relatively to provide a method ofproducing a motor fuel parafiinic and relatively non-paraffinichydrocarbons to a solvent extraction step, employing as the extractionsolvent a di-alkoxyalkyl phthalate in which each alkoxyalkyl groupcontains only two to six carbon atoms. I have found that suchalkoxyalkyl phthalates will extract the relatively non-paraffinichydrocarbons from such bydrocarbon oil and'will extract the hydrocarbonsof relatively high knock rating from a non-Viscous normally liquidpetroleum oil of motor fuel boiling range which comprises a mixture ofhydrocarbons of different knock ratings.

The hydrocarbon oils, which may be treated in accordance with myinvention, are those generally known as non-viscous normally liquidhydrocarbon oils of low molecular weight which are suitable for use ininternal combustion engines. They will generally have the followingcharacteristics:

% distillation point-not over 200 F. 90% distillation point-not over 395F. End distillation point--not over 450 F.

The hydrocarbon oils will generally be of petroleum origin, such as thestraight-run gasolines, cracked gasolines, reformed gasolines andpolymer 'gasolines, which oils of petroleum origin will be hereinafterreferred to as petroleum oils.

The solvents, to be employed in accordance with my invention, are thedi-alkoxyalkyl phthalates in which each alkoxyalkyl group contains onlytwo to six carbon atoms. They are di-alkoxyalkyl esters of phthalicacid. Preferably, the alkoxyalkyl radical or group contains only threeto four carbon atoms. Also, the di-methoxyalkyl phthalates in which eachalkyl group contains only two to three carbon atoms produce the bestresults. Amongst the compounds which I have found to be particularlysatisfactory are:

Di-methoxyethyl phthalate Di-methoxypropyl phthalate Di-butoxyethylphthalate The di-methoxyethyl phthalate becomes miscible only at about90 C. and permits phase separa-. tion at temperatures of about 25 C. andlower. The di-methoxypropyl phthalate permits phase separation at about0 C. The di-butoxyethyl phthalate permits phase separation at about 50C. and is applicable for extractions at low temperatures. Alkoxyalkylphthalates of intermediate numbers of carbon atoms will permit phaseseparation at intermediate temperatures.

In general, the method of my invention will comprise mixingapproximately equal volumes of solvent and hydrocarbon oil and heatingwith agitation to a temperature at which the solvent and oil becomecompletely miscible. The solution will then be cooled with agitation toa temperature substantially below the temperature of lit complete Uponset lg, layers will be f..n .1fl@d which separated, and

tillation :51 m the solvent, one or comprises components of the motorfuel d solved in the bulk oi. the liquid solvent, while the other iconsof rel rocar'bons atively sigh knock: ratin she from. the is, ercontaining the sma amount of solvent comprises primarily the rela elyparatrfinic constituents of low octane number and low knock The motorfuel, from the layer containing the larger amount solvent, the extractphase, may be employed per se as a high anti-knock; motor fuel or it maybe used for blending with an ordinary petroleum naphtha to increase theoctane value or knock rating of the naphtha. it may be used withoutfurther reing, if desired, or it maybe subjected to any DI the usualrefining treatments, such as disti1lation and the like.

Before subjecting the oil to the extraction treatment, it will generallybe desirable to top it of light ends to 95 C., that is, to boil off theconstituents boiling below 95 C. This is done to avoid handling lossesof gasoline by volatilization, as the light ends are generallysatisfactory as to lrnock rating.

the example given below, the selective re moval of the high anti-knockconstituents from a motor fuel has been measured by following the changein refractive index and aniline pointer the gasoline. The values ofthese constants for difierent hydrocarbon types is described in anarticle by F. D. Rossini in the Oil and Gas Journal, volume 36, November12, 1937, page 193 et seq, entitled A decade ,of research on thechemical constitution of petroleum. The values of the refractive indexincrease in the order paraffin, naphthene, and aromatic, and formolecules with 8 or 9 carbon atoms have the following approximatevalues: parafin 1.40; naphthene 1.425; aromatic 1.50. The criticalsolution temperature in aniline increases in the order aromatic,naphthene, and parafiin, and for molecules with about 8 carbon atoms hasthe following approximate values, respectively: 2il (3., 415 C. and 7lC. The aniline points of a large number of pure hydrocarbons will alsobe found in an article. by E. B. Evans entitled Aniline points ofhydrocarbons in the Journal of the Institution oi PetroleumTechnologists, volume 23, page 22c et seq. An increase m the refractiveindex and a decrease in the aniline point will thus indicate asegregation of the desirable types largely responsible for high octanevalue.

In order to minimize handling losses, selective solvent extraction ispreferably applied to gasolines having an initial boiling point of about200 F. (93 C.), which will in general necessitate a preliminary toppingoperation.

Example cooled arge proportion oi co al. volume of diqiethoxyethyl pheated to 52., which temperate and gasoline were im'scible. The so :o 5allowed to settle, U W ndrawn recovered from both layer on reducedpressure. The solvent to contain 8% by volume of the line. The extracthad a refractive index at of 1.4461, compared with a value of lxlficii bSore .3

extraction, and an aniline point of l2.l. 6., com" pared with a value of430 C. before extractio The above example is merely illustrative of rntion and my invention is not to be thereto. I be made "in the processand the conditions em ployed Without departing from the spirit ofinvention. Also, other di'alkoxyallryl phthalates may be substituted forthe di-methoxyethyl phthalate. phthalates are:

Di inethoizymethyl phthalate Di-methoxybutyl phthalate Di-ethoxymethylphthalate Di-ethoxyethyl phthalate Di-ethoxypropyl phthalateDi-ethoxybutyl phthalate Di-propoxymethyl phthalate Di-propoxyethylphthalate Di-propoxypropyl phthalate Dl-butoxymethyl phthalate Also,di-alkoxyalkyl phthalates, containing two different allzoxyalirylgroups, maybe employed.

Further, mixtures of two or more difierent din and doctor treatmentapplied either before or after the solvent extraction. Also, theconditions of the applicationof the solvent may vary with the nature ofthegasoline being treated and the improvement in anti-knock ratingdesired. It may be desirable to carry out the extraction with arelatively large volume of solvent, for example several hundred percent.In some cases, it may be desirable to carry out the extractionwith lessthan equal volume of solvent. However, approximately equal volumes ofsolvent and gasoline will usually be employed. The solvent and gasolinemay be mixed and separated in a batch operation or in a countercurrentoperation. the temperature for the formation of two phases may vary,depending upon the particular gasoline and solvent selected, but willgenerally range from about l0 C. to about 50 C. v

My invention has the advantage of providing stable neutral solventswhich will have no tend-= ency to react with the constituents of thegasoline. The solvents have boiling points sufiiciently high to permitseparation or the gasoline therefrom by a simple distillation. Thesolvents have mis cibility characteristics which permit them to beemployed without other materials such as precipitants and the like. Ascompared with my compounds, other somewhat related alkoxyallrylvariations and modifications may 1 Some of such other di=-alkoxyalhylesters, such as di-butoxyethyl fumarate, di=- butoxyethyl succinate anddi-butoxyetlryl adipate, 75,

do not form twophases with the gasoline of the example at temperatureseven as low as -50 C.

I claim:

1. The method of treating a non-viscous normally liquid hydrocarbon oilof motor fuel boiling range containing relatively parafiinic andrelatively non-parafiinic hydrocarbons which comprises extracting theoil in the liquid phase with a di-alkoxyalkyl phthalate in which eachalkoxyalkyl group contains only two to six carbon atoms, to separate therelatively non-parafiinic hydrocarbons from the relatively paraflinichydrocarbons.

2. The method of treating a non-viscous normally liquid hydrocarbon oilof motor fuel boiling range containing relatively paraflinic andrelatively non-paraflinic hydrocarbons which comprises extracting theoil in the liquid phase with a di-alkoxyalkyl phthalate in which eachalkoxyalkyl group contains only three to four carbon atoms, to separatethe relatively nonparafilnic hydrocarbons from the relatively paraffinichydrocarbons.

3. The method of treating a non-viscous normally liquid hydrocarbon oilof motor fuel boiling range containing relativelyparaflinic andrelatively non-paraflinic hydrocarbons which cornprises extracting theoil in the liquid phase with a di-methoxyalkyl phthalate in which eachalkyl group contains only one to four carbon atoms, to separate therelatively no-paraflinic hydrocarbons from the relatively paraffinichydrocarbons.

4. The method of treating a non-viscous normally liquid hydrocarbon oilof motor fuel boiling range containing relatively paraiiinic andrelatively non-parafiinic hydrocarbons which comprises extracting theoil in the liquid phase with a di-methoxyalkyl phthalate in which eachalkyl group contains only two to three carbon atoms, to separate therelatively non-paraflinic hydrocarbons from the relatively paraiilnlchydrocarbons.

5. The method of treating a non-viscous normally liquid hydrocarbon oilof motor fuel boiling range containing relatively paraiiinic andrelatively -'non-paraffinic hydrocarbons which comprises extracting theoil in the liquid phase with a di-alkoxyethyl phthalate in which eachalkoxy group contains only one to four carbon atoms, to separate therelatively non-paraflinic hydrocarbons from the relatively paraiiinichydrocarbons.

6.. The method of treating a non-viscous nor mally liquid hydrocarbonoil of motor fuel boiling range containing relatively parafilnic andrelatively non-paraflinic hydrocarbons which comprises extracting theoil in the liquid phase with a di-alkoxyethyl phthalate in which eachalkoxy group contains only one to two carbon atoms, to'separate therelatively non-paraflinic hydrocarbons from the relatively paraflinichydrocarbons. V

7. The method of treating an non-viscous normally liquid hydrocarbon oilof motor fuel bolling range containing relatively paraflinic andrelatively non-paraflinic hydrocarbons which comprises extracting theoil in the liquid phase with di-methoxyethyl phthalate, to separate therelatively non-parafflnic hydrocarbons from the relatively paramnichydrocarbons.

8. The method of treating a non-viscous normally liquid hydrocarbon oilof motor fuel boiling range containing relatively paraflinic andrelatively non-parafiinic hydrocarbons which comprises extracting theoil in the liquid phase with di-methoxypropyl phthalate, to separate therelatively non-paraffinic hydrocarbons'from the relatively paramnichydrocarbons.

9. The method of producing a motor fuel of improved knock rating from anon-viscous normally liquid petroleum oil of motor fuel boiling rangecomprising a mixture of hydrocarbons of different knock ratings whichcomprises mixing the oil in the liquid phase with a di-alkoxyalkylphthalate in which each alkoxyalkyl group contains only two to sixcarbon atoms, forming an extract phase containing hydrocarbons ofrelatively high knock rating dissolved in the phthalate and a raffinatephase comprising hydrocarbons of relatively low knock rating, separatingthe two phases and removing the hydrocarbons from the phthalate.

10. The method of producing a motor fuel of improved knock rating from astraight-run gasoline which comprises extracting the gasoline in.

the liquid phase with a di-alkoxyalkyl phthalate in which eachalkoxyalkylgroup contains only two to six carbon atoms to separate thecompounds of higher knock rating from the gasoline.

11. The method of producing a motor fuel of improved knock rating from astraight-run gasoline which comprises extracting the gasoline in theliquid phase with a di-alkoxyalkyl phthalate in which each alkoxyalkylgroup contains only three to four carbon atoms to separate the compoundsof higher knock rating from the gasoline.

12. The method of producing a motor fuel of improved knock rating from astraight-run gasoline which comprises extracting the gasoline in theliquid phase with a di-methoxyalkyl phthalate in which each alkyl groupcontains only two to three carbon atoms to separate the compounds ofhigher knock rating from the gasoline.

13. The method of producing a motor fuel of improved knock rating from astraight-run gasoline which comprises extracting the gasoline in theliquid phase with a di-alkoxyethyt phthalate in which each alkoxy groupcontains only one to two carbom atoms to separate the compounds ofhigher knock rating from thegasoline.

14. The method of producing a motor fuel of improved knock rating from astraight-run gasoline which comprises extracting the gasoline in theliquid phase with di-methoxyethyl phthalate to separate the compounds ofhigher knock rating from the gasoline. v

15. The method of treating a non-viscous normally liquid hydrocarbon oilof motor fuel boiling range containing relatively paraflinic andrelatively non-parafiinic hydrocarbons which comprises extracting theoil in the liquid phase with di-butoxymethyl phthalate, to separate therelatively non-paraillnic hydrocarbons from the relatively parafllnichydrocarbons.

16. The method of producing a motor fuel of improved knock rating from astraight-run gasoline which comprises extracting the gasoline in theliquid phase with di-butoxymethyl phthalate CERTIFICATE OF CORRECTION.Patent No. 2,221,814.6- November 19, 191 0.

WILBUR B. PINGS.

It is hereby certified that error appears in the printeqi specificationof the above nnmbered patent requiring correction as follows: Page 5first column, line 51, claim3, for "noparaffinic" reed--non-p'araffinic--; line 634., claim 7, for "an" read -a--; and secondcolumn, line 69; claim 17, for "improced" read --improved; and that thesaid Letters Patent should be read with this correction therein'that thesame may conform to the record of the case in the Patent Office.

Signed and sealed this al en day of December, A. D. 191 0.

Henry Van Arsdale, (Seal) Acting Comniissioner of Patents

